Terahertz active spatial filtering through optically tunable hyperbolic metamaterials

TL;DR

This paper proposes a tunable terahertz spatial filter using hyperbolic metamaterials whose properties are controlled by infrared radiation, enabling dynamic control over terahertz wave propagation.

Contribution

It introduces a theoretical design of an infrared-controlled hyperbolic metamaterial for active terahertz spatial filtering with tunable bandwidth.

Findings

Metamaterial hyperbolic dispersion enables spatial frequency filtering.

Infrared radiation intensity controls the bandwidth of filtering.

Numerical simulations confirm device functionality.

Abstract

We theoretically consider infrared-driven hyperbolic metamaterials able to spatially filtering terahertz radiation. The metamaterial is a slab made of alternating semiconductor and dielectric layers whose homogenized uniaxial response, at terahertz frequencies, shows principal permittivities of different signs. The gap provided by metamaterial hyperbolic dispersion allows the slab to stop spatial frequencies within a bandwidth tunable by changing the infrared radiation intensity. We numerically prove the device functionality by resorting to full wave simulation coupled to the dynamics of charge carries photoexcited by infrared radiation in semiconductor layers.